Design And Build of A Total Dissolved Solid (Tds) Control System to Maintain Water Quality in Koi Fish Ponds

Koi fish (Cyprinus carpio) is one of the types of ornamental fish with high economic value that is highly sought after by many people every year. Despite having high economic value and a large number of enthusiasts, it turns out that Koi fish farming is not easy. Koi fish are prone to sensitivity to changes in water parameters, one of which is Total Dissolved Solids (TDS). The TDS content is influenced by organic matter such as fish waste, leftover feed, and ions in the water such as calcium, phosphate, nitrate, sodium, potassium, magnesium, bicarbonate, carbonate, and chloride. The acceptable TDS level tolerated by Koi fish is 500 ppm. If the TDS level exceeds 500 ppm, it is feared that it can affect the health and growth of Koi fish, such as damage to the gills, hindered growth rate, and susceptibility to diseases. The design of the TDS control system is done by measuring the TDS value in the water. If the TDS value exceeds the predetermined setpoint, the system automatically performs water replacement. This control system is also equipped with four additional sensors to monitor water parameters, including Dissolved Oxygen (DO) sensor, pH sensor, turbidity sensor, and temperature sensor for monitoring water quality. The validation process of these five sensors resulted in an error percentage of less than 5% with an accuracy of over 95%, which is considered competent for use in the created control system. The on/off control system has successfully reduced the water TDS from the highest recorded value of 534 ppm to 369 ppm when the control system has completed its operation.